The belief that humanure is unsafe for agricultural use is called fecophobia,
a term, I admit, I made up. People who are fecophobic can suffer from severe
fecophobia or a relatively mild fecophobia, the mildest form being little more
than a healthy concern about personal hygiene. Severe fecophobics do not want
to use humanure for food growing, composted or not. They believe that it's dangerous
and unwise to use such a material in their garden. Milder fecophobics may, however,
compost humanure and use the finished compost in horticultural applications.
People who are not fecophobic may compost humanure and utilize it in their food
garden. Some may even use it raw, a practice not recommended by the author.

It is well known that humanure contains the potential to harbor disease-causing
microorganisms (pathogens). This potential is directly related to the state
of health in the population which is producing the excrement. If a family is
composting its own humanure, for example, and it is a healthy family, the danger
in the production and use of the compost will be very low. If one is composting
the humanure from orphanages in Haiti where intestinal parasites are endemic,
then extra precautions must be taken to ensure maximum pathogen death. Compost
temperatures must rise significantly above the temperature of the human body
(37°C or 98.6°F) in order to begin eliminating disease-causing organisms, as
human pathogens thrive at temperatures similar to that of their hosts. On the
other hand, most pathogens only have a limited viability outside the human body,
and given enough time, will die even in low-temperature compost.

Humanure is best rendered hygienically safe by thermophilic composting. To
achieve this, humanure can simply be collected and deposited on an outdoor compost
pile like any other compost material. Open-air, outdoor compost piles with good
access are easily managed and offer a no-cost, odorless method to achieve the
thermophilic composting of humanure. However, such a system does require the
regular collection and cartage of the organic material to the compost pile,
making it relatively labor intensive when compared to low-temperature, stationary,
homemade and commercial composting toilets.

Many people will use a composting toilet only if they do not have to do anything
in any way related to the toilet contents. Therefore, most homemade and commercial
composting toilets are comprised of large composting chambers under the toilet
seat. The organic material is deposited directly into a composting chamber,
and the contents are emptied only very occasionally.

Thermophilic conditions do not seem to be common in these toilets, for several
reasons. For one, many commercial composting toilets are designed to dehydrate
the organic material deposited in them. This dehydration is achieved by electrical
fans, which rob the organic mass of moisture and heat. Commercial toilets also
often strive to reduce the quantity of material collecting in the composting
chamber (mostly by dehydration), in order to limit the frequency of emptying
for the sake of the convenience of the user. Bulky air-entrapping additions
to the compost are not encouraged, although these additions will encourage thermophilic
composting. Yet, even passive, low-temperature composting will eventually yield
a relatively pathogen-free compost after a period of time.

Low-temperature composting toilets include most commercial and many homemade
units. According to current scientific evidence, a few months retention time
in just about any composting toilet will result in the deaths of nearly all
human pathogens (see Chapter 7). The most persistent
pathogen seems to be the roundworm (Ascaris lumbricoides) and particularly
the egg of the roundworm, which is protected by an outer covering which resists
chemicals and adverse environmental conditions. Estimates of the survival time
of Ascaris eggs in certain soil types under certain conditions are as
high as ten years. Although the Ascaris eggs are readily destroyed by
thermophilic composting, they may survive in conditions generated by a low-temperature
toilet. This is why the compost resulting from such toilets is generally not
recommended for garden use if it comes in contact with food crops.

People can become rather obsessive about this issue. One man who published
a book on this topic wrote to me to say that a two year retention time in a
low-temperature composting toilet is generally considered adequate for the destruction
of Ascaris ova (eggs). He indicated that he would never consider using
his own low-temperature compost until it had aged at least two years. I asked
him if he was infected with roundworms. He said no. I asked him if anyone else
was using his toilet. No. I asked him what he was worried about then. Why would
he think there could be roundworm eggs in his compost when he knew he didn't
have roundworms in the first place? Sometimes common sense is not so common.
The potential dangers of humanure can be blown way out of proportion.
This is similar to the phobic person who would never go to a movie theater because
there may be someone in the theater who has tuberculosis and who may sneeze.
Although this is a risk we all take, it's not likely to be a problem.